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Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team standing on Hereford Street near the intersection of Manchester Street. In the background is the Hotel Grand Chancellor. The hotel has a noticeable slump on the left side.

Images, UC QuakeStudies

A photograph of the Wellington Emergency Management Office Emergency Response Team walking down Lichfield Street. Plastic fencing and road cones have been placed along both sides of the road as cordons. Behind the fences are piles of bricks and other rubble from the buildings above.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the Red Cross, standing on the corner of Lichfield and Manchester Street. In the background an excavator is parked on the road. Behind the excavator is a block of earthquake-damaged buildings.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team walking down Manchester Street. In the background is a group of earthquake-damaged shops. The outer walls of the top storeys of the shops have collapsed, the bricks spilling onto the street.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team in Latimer Square. In the background, another emergency management team is sitting next to a tent. Other tents are dotted around the square. A cherry picker is also sitting in the background.

Images, UC QuakeStudies

A photograph of the Copthorne Hotel on the corner of Kilmore and Durham Streets. Tape has been draped around the footpath in front of the building. A member of the Wellington Emergency Management Office Emergency Response Team is walking through the intersection below.

Research papers, The University of Auckland Library

The full scale, in-situ investigations of instrumented buildings present an excellent opportunity to observe their dynamic response in as-built environment, which includes all the real physical properties of a structure under study and its surroundings. The recorded responses can be used for better understanding of behavior of structures by extracting their dynamic characteristics. It is significantly valuable to examine the behavior of buildings under different excitation scenarios. The trends in dynamic characteristics, such as modal frequencies and damping ratios, thus developed can provide quantitative data for the variations in the behavior of buildings. Moreover, such studies provide invaluable information for the development and calibration of realistic models for the prediction of seismic response of structures in model updating and structural health monitoring studies. This thesis comprises two parts. The first part presents an evaluation of seismic responses of two instrumented three storey RC buildings under a selection of 50 earthquakes and behavioral changes after Ms=7.1 Darfield (2010) and Ms=6.3 Christchurch (2011) earthquakes for an instrumented eight story RC building. The dynamic characteristics of the instrumented buildings were identified using state-of-the-art N4SID system identification technique. Seismic response trends were developed for the three storey instrumented buildings in light of the identified frequencies and the peak response accelerations (PRA). Frequencies were observed to decrease with excitation level while no trends are discernible for the damping ratios. Soil-structure interaction (SSI) effects were also determined to ascertain their contribution in the seismic response. For the eight storey building, it was found through system identification that strong nonlinearities in the structural response occurred and manifested themselves in all identified natural frequencies of the building that exhibited a marked decrease during the strong motion duration compared to the pre-Darfield earthquakes. Evidence of foundation rocking was also found that led to a slight decrease in the identified modal frequencies. Permanent stiffness loss was also observed after the strong motion events. The second part constitutes developing and calibrating finite element model (FEM) of the instrumented three storey RC building with a shear core. A three dimensional FEM of the building is developed in stages to analyze the effect of structural, non-structural components (NSCs) and SSI on the building dynamics. Further to accurately replicate the response of the building following the response trends developed in the first part of the thesis, sensitivity based model updating technique was applied. The FEMs were calibrated by tuning the updating parameters which are stiffnesses of concrete, NSCs and soil. The updating parameters were found to generally follow decreasing trends with the excitation level. Finally, the updated FEM was used in time history analyses to assess the building seismic performance at the serviceability limit state shaking. Overall, this research will contribute towards better understanding and prediction of the behavior of structures subjected to ground motion.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the New Zealand Police inspecting the Cherish Bridal and Formal Wear store on Montreal Street. Inside the store one of the ERT members is attempting to break through a wall.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team standing on the corner of Lichfield and Manchester Streets. In the background an excavator has been parked on the street. In the background is a large pile of rubble from several earthquake-damaged buildings.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the New Zealand Police inspecting the Cherish Bridal and Formal Wear store on Montreal Street. Inside the store one of the ERT members is attempting to break through a wall.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the New Zealand Police inspecting the Cherish Bridal and Formal Wear store on Montreal Street. Inside the store one of the ERT members is attempting to break through a wall.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team and the Red Cross working on High and Manchester Streets. On both sides of the street there are piles of rubble from the earthquake-damaged buildings. Several excavators have been parked in a line along the street.

Images, UC QuakeStudies

A photograph of the Wellington Emergency Management Office Emergency Response Team standing in a car park on Lichfield Street. The team are wearing face and gas masks, hard hats, safety glasses, knee pads, and rubber gloves. In the background are several earthquake-damaged buildings.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team standing on the intersection of Manchester and Lichfield Streets. In the background is the Majestic Theatre. Piles of rubble from earthquake-damaged buildings has been piled on the road below the building.

Images, UC QuakeStudies

A photograph of an excavator clearing the rubble from earthquake-damaged buildings on Lichfield Street. The rubble has been gathered from the street and piled up beside the Majestic Theatre. In the foreground a member of the Wellington Emergency Management Office Emergency Response Team is crossing the street.

Images, UC QuakeStudies

A photograph of a map used by the Wellington Emergency Management Office Emergency Response Team. The block of buildings between Montreal, Acton, St Asaph, and Antigua Streets has been outlined in red. Halkett Street has also been coloured in red. Various buildings around these areas have been highlighted in orange and blue.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team standing on the bank of the Avon River. In the background are the remains of the collapsed PGC Building. An excavator is on top of these remains, working to clear them away.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team standing on the bank of the Avon River. In the background are the remains of the collapsed PGC Building. An excavator is on top of these remains, working to clear them away.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team pointing to an earthquake-damaged house in central Christchurch. A large section of the house has collapsed, the rubble spilling onto the driveway. Emergency tape has been draped across the driveway as a cordon.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team walking through the intersection of Manchester and Gloucester Streets. In the background, Manchester Street has been cordoned off with wire fences and is littered with rubble. Many of the buildings in view are severely damaged.

Images, UC QuakeStudies

A photograph of a member of the Wellington Emergency Management Office Emergency Response Team inside an office. In the foreground, the drawers of filing cabinets have opened. Files and posters litter the ground. The coverings over the lights have shaken loose, and one is hanging just behind the ERT member.

Research papers, The University of Auckland Library

Soil-structure interaction (SSI) has been widely studied during the last decades. The influence of the properties of the ground motion, the structure and the soil have been addressed. However, most of the studies in this field consider a stand-alone structure. This assumption is rarely justifiable in dense urban areas where structures are built close to one another. The dynamic interaction between adjacent structures has been studied since the early 1970s, mainly using numerical and analytical models. Even though the early works in this field have significantly contributed to understanding this problem, they commonly consider important simplifications such as assuming a linear behaviour of the structure and the soil. Some experimental works addressing adjacent structures have recently been conducted using geotechnical centrifuges and 1g shake tables. However, further research is needed to enhance the understanding of this complex phenomenon. A particular case of SSI is that of structures founded in fine loose saturated sandy soil. An iconic example was the devastating effects of liquefaction in Christchurch, New Zealand, during the Canterbury earthquake in 2011. In the case of adjacent structures on liquefiable soil, the experimental evidence is even scarcer. The present work addresses the dynamic interaction between adjacent structures by performing multiple experimental studies. The work starts with two-adjacent structures on a small soil container to expose the basics of the problem. Later, results from tests considering a more significant number of structures on a big laminar box filled with sand are presented. Finally, the response of adjacent structures on saturated sandy soil is addressed using a geotechnical centrifuge and a large 1g shake table. This research shows that the acceleration, lateral displacement, foundation rocking, damping ratio, and fundamental frequency of the structure of focus are considerably affected by the presence of neighbouring buildings. In general, adjacent buildings reduced the dynamic response of the structure of focus on dry sand. However, the acceleration was amplified when the structures had a similar fundamental frequency. In the case of structures on saturated sand, the presence of adjacent structures reduced the liquefaction potential. Neighbouring structures on saturated sand also presented larger rotation of the footing and lateral displacement of the top mass than that of the stand-alone case.

Research papers, University of Canterbury Library

Research following the 2010-2011 Canterbury earthquakes investigated the minimum vertical reinforcement required in RC walls to generate well distributed cracking in the plastic hinge region. However, the influence of the loading sequence and rate has not been fully addressed. The new minimum vertical reinforcement limits in NZS 3101:2006 (Amendment 3) include consideration of the material strengths under dynamic load rates, but these provisions have not been validated at a member or system level. A series of tests were conducted on RC prisms to investigate the effect of loading rate and sequence on the local behaviour of RC members. Fifteen axially loaded RC prisms with the designs representing the end region of RC walls were tested under various loading rates to cover the range of pseudo-static and earthquake loading scenarios. These tests will provide substantial data for understanding the local behaviour of RC members, including hysteretic load-deformation behaviour, crack patterns, failure mode, steel strain, strain rate and ductility. Recommendations will be made regarding the effect of loading rate and reinforcement content on the cracking behaviour and ductility of RC members.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team examining an earthquake-damaged building on Acton Street. The closest section of the outer wall has collapsed, and the bricks and other rubble have fallen onto the pavement in front. A boat which was being stored inside has toppled over and is now sticking out of the building.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team examining an earthquake-damaged building on Acton Street. The closest section of the outer wall has collapsed, and the bricks and other rubble have fallen onto the pavement in front. A boat which was being stored inside has toppled over and is now sticking out of the building.